In a known method of this kind, an electric motor is combined, for example, with a recirculating ball steering system. Due to the friction within the steering system, the reaction of the forces acting on the steering from the road is damped. The friction leads to a so-called torque hysteresis of the steering gear, that is, opposing steering torques do not have the direct effect of torque at the output of the gear. A disadvantage of this method is the fact that the steering comfort is not optimal at all vehicle speeds due to the fixed hysteresis.
Various methods for improving the characteristics of a steering assistance system are described in published British patent application GB 2 163 110 A and the Japanese patent abstract 63-301173 (A). It has been found that these methods do not cover all driving conditions with regard to a high steering comfort and a good contact of the driver with the roadway since the characteristics of the steering gear are largely not taken into account.